Phonetic keys for the English language have been used in many applications. In computer-related applications, phonetic keys can be used for data searching and database record searching. Typically, a phonetic key is a series of characters that capture the sound of one or more words. The characters in a phonetic key can include a combination of numbers, symbols, and alphabets.
Several methods have been developed to produce phonetic keys for a given word in English or some Latin-based languages. Soundex, Metaphone, and Double Metaphone are some of the methods used for producing phonetic keys. Soundex technique produces a phonetic code consisting of a letter followed by three numbers. Generally, the letter is the first letter of a word, and the numbers encode the remaining consonants. The Metaphone method produces variable-length phonetic keys unlike the fixed-length keys of the Soundex method. Similar sounding words share the same keys in the Metaphone method. The Double Metaphone method produces two phonetic keys, namely, a variable-length primary key as in the Metaphone method and a variable-length secondary key to account for alternate pronunciations.
However, Soundex, Metaphone, Double Metaphone, and other similar methods are suitable for English and Latin-based languages. These methods may not be applicable to complex languages such as the Japanese language. Developing phonetic keys for the Japanese language would be desirable.